Manufacturing method for filter module

ABSTRACT

The measurement and adjustment of characteristics of a filter alone are performed using a connector adapter, in which a pin of the filter becomes a central conductor of the adapter. The filter after the adjustment and a device which is not adjusted are assembled, such that the filter and the device are connected by connecting the pin provided in the filter and a transmission line provided in the device. Accordingly, the time for adjustment is shortened and the adjustment for obtaining the desired characteristics of the filter module are made easy.

DETAILED DESCRIPTION OF THE INVENTION

[0001] 1. Technical Field of the Invention

[0002] The present invention relates to a manufacturing method for afilter module containing a filter and a device except the filter.

[0003] 2. Description of the Related Art

[0004] A filter module containing a filter and a low-noise amplifier(LNA) is disclosed in Japanese Unexamined Patent Application PublicationNo. 5-83147. In the filter module, the filter and the LNA are housed inthe same case, and the LNA is directly connected to a coupling line ofthe output portion of the filter.

[0005] In this way, the characteristics of the filter and the LNA can bemonitored and adjusted by using the coupling line.

[0006] However, in such filter modules having a filter and a devicedirectly connected and housed in the same case, since the filter and thedevice are required to be adjusted together, there is a problem in thatit takes time to adjust them. Furthermore, when the filter and thedevice are combined, since the characteristics of each of them are notknown, it is not easy to adjust them.

SUMMARY OF THE INVENTION

[0007] Accordingly, it is an object of the present invention to providea manufacturing method for a filter module in which the time foradjustment is shortened and the adjustment for obtaining fixedcharacteristics is made easy.

[0008] According to a manufacturing method for a filter module of thepresent invention, a device, characteristics measurement of which hasbeen made, and a filter, characteristics adjustment of which is to bemade, are provided to manufacture a filter module.

[0009] The required characteristics of the filter are first determinedfrom the characteristics of the device and target characteristics of thefilter module.

[0010] Then, the characteristics of the filter alone are measured. Fromthe characteristics and the required characteristics, adjustmentlocations and adjustment amounts of the filter are determined so as tomeet the required characteristics, and then the adjustment is carriedout.

[0011] After the adjustment is carried out, the filter and the deviceare combined to form the filter module.

[0012] In the manufacturing method for a filter module according to thepresent invention, the connection between the filter and the device ispreferably made by connecting a pin provided in the filter to atransmission line provided in the device, and the characteristics of thefilter alone are measured by attachment of a connector adapter in whichthe pin constitutes a center conductor.

[0013] In a preferred manufacturing method for a filter module accordingto the present invention, the device is a circuit constructed on asubstrate, and the filter is provided with a concave portion into whichthe substrate is fitted.

[0014] Furthermore, in the manufacturing method for a filter moduleaccording to the present invention, the device is preferably a low-noiseamplifier and the filter is connected in a front stage or rear stage ofthe low-noise amplifier.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIGS. 1A and 1B are block diagrams showing a filter module and afilter, respectively.

[0016] FIGS. 2A-2C are perspective views showing the construction of afilter, device, and filter module.

[0017] FIGS. 3A-3D are partial perspective views showing theconstruction of the connection portion between a filter and a device.

[0018]FIG. 4 is a flow chart showing the processes of a manufacturingmethod for a filter module.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, a manufacturing method for a filter module will bedescribed with reference to the accompanying drawings.

[0020]FIG. 1A is a block diagram showing the construction of a filtermodule at the time when the filter module and its characteristics areadjusted. FIG. 1B shows the construction of a filter 10 separated from adevice 20. As is shown in FIG. 1A, the filter module is constructed suchthat the device 20 (LNA) is provided in a latter stage of the filter 10.In the manufacturing method for a filter module according to the presentinvention, the device 20, the characteristics of which are known, isused and the measurement and adjustment of the characteristics of thefilter 10 alone are performed.

[0021]FIGS. 2A through 2C are perspective views showing the constructionof the filter, device, and filter module, respectively. FIG. 2A showsthe construction of the filter alone. The filter 10 is provided with aconnector 14 for connection to the outside. The filter 10 is alsoprovided with a concave portion 11 into which a substrate constitutingthe device is fitted. A pin 12 for connection to a transmission line ofthe device is provided in the concave portion 11 of the filter 10. Thisfilter 10 can be used as a dielectric filter in which electrodes areprovided inside and outside a dielectric block, or as a dielectricfilter in which a dielectric resonator is disposed inside a cavity.Furthermore, the filter 10 is provided with a frequency adjustment screw(not shown) for adjusting a frequency as required.

[0022] In FIG. 2A, reference numeral 13 represents a connector adapter.When the connector adapter 13 is attached to the pin 12, a coaxialconnector having the connector adapter 13 as an outer conductor and thepin 12 as a central conductor is constructed. In that state, the frontend of the filter can be connected to the outside through the connector14 and the rear end of the filter can be connected to the outsidethrough the coaxial connector made up of the connector adapter 13 andthe pin 12.

[0023]FIG. 2B shows how the device 20 is fitted into the filter 10. Thedevice 20 shown in FIG. 2B is formed as a circuit board. A connector 21for connection to the outside is provided in the device 20. The device20 is electrically connected to the filter 10 by fitting the device 20into the concave portion of the filter 10 and preferably soldering thepin 12 of the filter 10 to a transmission line of the device 20.Reference numeral 30 represents a protective cover which covers thedevice 20. Thus, a filter module 100 is constructed as shown in FIG. 2C.

[0024]FIGS. 3A through 3D show how the connector adapter 13 is attachedto the pin 12 of the above filter, and how the device 20 is connected tothe filter. In the filter alone, the connector on the output side of thefilter is made such that the connector adapter 13 is attached to the pin12 as shown in FIG. 3A. After the characteristics of the filter alonehas been measured and adjusted, the connector adapter 13 is removed asshown in FIG. 3B, and the filter and the device are electricallyconnected such that the transmission line 22 is soldered to the pin 12of the filter as shown in FIGS. 3C and 3D.

[0025]FIG. 4 is a flow chart showing the processes of the manufacturingmethod for a filter module according to the present invention. In thisinvention, adjustments are preferably not performed for the variationsin manufacture of the device (LNA) to be used in the filter module, butrather, the characteristics of the filter module are set to satisfy afixed specification by adjustment of only the filter portion.

[0026] The required characteristics of the filter are determined fromcharacteristics of the device and target characteristics of a filtermodule (n1). Preferably, the characteristics of the filter module arenormalized using S parameters. The S parameters of the device withoutthe filter are measured using a network analyzer in advance. Then, byusing a high-frequency simulator, the S parameters of the filter thatsatisfy the normalized S parameters of the filter module are determinedfrom the normalized S parameters of the filter module and the Sparameters of the device.

[0027] Next, the characteristics of the filter alone are measured, andadjustment locations and adjustment amounts of the filter are determinedfrom the measured characteristics of the filter and the requiredcharacteristics of the filter (n3 and n3). Preferably, the upper limitand lower limit of each element (equivalent capacitance, inductance,etc.) constituting the filter is set in advance, and the value of eachelement constituting the filter is determined so as to meet the target Sparameters of the filter by using the high-frequency simulator.Moreover, since each element of the filter practically has its ownadjustable range different from each other, this is input in advance.

[0028] Next, the determined value of each element constituting thefilter is input into a computer, the computer is connected to thenetwork analyzer, and the filter is connected to the network analyzer.As commonly conducted in the field of filter designing, calculations areperformed to determine what part of the filter is to be cut to whatlevel, the frequency adjustment screw of which resonator is to beturned, etc., and they are adjusted so that the required S parametersmay be satisfied (n4).

[0029] Then, the filter and the device are assembled to produce a filtermodule (n5). Thereafter, the characteristics of the filter module aremeasured, it is judged whether the characteristics are in a specifiedrange or not, and whether the filter module passes and is accepted as aconforming filter module (n6 and n7).

[0030] According to the present invention, the device is not adjustedand the measurement and adjustment of the filter alone is made possible.Accordingly, the time required for adjustment is shortened andadjustment of the filter module characteristics can be easily made.

[0031] Furthermore, according to the present invention, since a filtercan be connected to the outside in order to measure the characteristicsof the filter at the portion of the filter where the a device is laterconnected, the measurement of the characteristics of the filter alonecan be securely performed without being affected by any other element.Therefore, desired characteristics of a filter module can be easilyobtained only by the adjustment of the filter.

[0032] Furthermore, according to the present invention, since a filteris provided with a concave portion into which a device constructed on asubstrate is fitted, the filter and the device are easily assembled.

[0033] Furthermore, according to the present invention, since the deviceis a low-noise amplifier (LNA), a low-noise amplifier the transmissionloss of which is low and which is of small size can be constructed.

[0034] Although the present invention has been described in relation toparticular embodiments thereof, many other variations and modificationsand other uses will become apparent to those skilled in the art. It ispreferred, therefore, that the present invention be limited not by thespecific disclosure herein, but only by the appended claims.

What is claimed is:
 1. A manufacturing method for a filter modulecontaining a device, characteristic measurement of which has been made,and a filter, characteristics adjustment of which is to be made, themethod comprising: determining required characteristics of the filterfrom the characteristic measurement of the device and targetcharacteristics of the filter module; measuring characteristics of thefilter alone; making characteristic adjustment of the filter such thatadjustment locations and adjustment amounts for meeting the requiredcharacteristics of the filter are determined from the characteristics ofthe filter alone and the required characteristics; and combining thefilter, the characteristic adjustment of which has been made, and thedevice by connection thereof.
 2. The manufacturing method for a filtermodule as claimed in claim 1, wherein the connection between the filterand the device is made by connecting a pin provided in the filter to atransmission line provided in the device, and wherein thecharacteristics of the filter alone are measured by attachment of aconnector adapter in which the pin constitutes a center conductor. 3.The manufacturing method for a filter module as claimed in claim 2,wherein the device is a circuit constructed on a substrate and wherein aconcave portion into which the substrate is fitted is provided in thefilter.
 4. The manufacturing method for a filter module as claimed inclaim 3, wherein the device is a low-noise amplifier and wherein thefilter is connected in one of a front stage and a rear stage of thelow-noise amplifier.
 5. The manufacturing method for a filter module asclaimed in claim 2, wherein the device is a low-noise amplifier andwherein the filter is connected in one of a front stage and a rear stageof the low-noise amplifier.
 6. The manufacturing method for a filtermodule as claimed in claim 1, wherein the device is a circuitconstructed on a substrate and wherein a concave portion into which thesubstrate is fitted is provided in the filter.
 7. The manufacturingmethod for a filter module as claimed in claim 6, wherein the device isa low-noise amplifier and wherein the filter is connected in one of afront stage and a rear stage of the low-noise amplifier.
 8. Themanufacturing method for a filter module as claimed in claim 1, whereinthe device is a low-noise amplifier and wherein the filter is connectedin one of a front stage and a rear stage of the low-noise amplifier.